Quarterly earnings misses and underwhelming guidance make these names the three worst performers in the stock market today

The stock market was a sea of red today, with losers outnumbering winners by a 4-to-1 margin. Unfortunately the catalyst behind Thursday's sell-off was the tragic loss of human life, as a Malaysia Airlines plane, with 295 people on board, was gunned down in eastern Ukraine by as-yet-unidentified forces. All 10 sectors ended in the red today, and shares of SanDisk(NASDAQ:SNDK), Mattel(NASDAQ:MAT), and Danaher(NYSE:DHR) finished toward the bottom of the S&P 500 Index(SNPINDEX:^GSPC). The S&P itself lost 23 points, or 1.2%, to end at 1,958.

Shares of flash memory provider SanDisk plunged 13.6%, ending as the single worst-performing stock in the S&P 500 today. Although SanDisk managed to beat both top- and bottom-line forecasts for the second quarter, investors own a company's future, not its past. SanDisk's future doesn't look quite as rosy as Wall Street anticipated: The company projected third-quarter revenue between $1.67 billion and $1.725 billion, where analysts had expected $1.74 billion. The projected sales miss doesn't quite justify the stock's free fall today, but if SanDisk routinely lowers its guidance in the quarters and years ahead, it will be fair to assume that trouble is brewing.

Trouble is almost certainly brewing at toy-maker Mattel; the company's shares shed 6.6% Thursday. "What's the trouble?" you might ask. Before I tell you, you may want to send any young children intently reading this article over your shoulder to another room. It's best that they don't see the disturbing truth spelled out so bluntly: Barbie is dying. While it's common knowledge that Barbie has retained her famed physique for more than five decades, the 55-year-old Barbie is suffering from a condition that can prove fatal for many toys: declining sales. Barbie sales, which are estimated to be around $1 billion a year and account for roughly 15% of Mattel's total sales, have slumped in eight of the last 10 quarters, and fell 15% in the second quarter.

Quarterly earnings at diversified machinery titan Danaher sent the stock tumbling today, as it lost 5.6% by the ring of the closing bell. Adjusted earnings per share in the second quarter came out to $0.93 per share, missing estimates by $0.01. Second-quarter revenue also missed, coming in at $4.96 billion against the $4.97 billion Wall Street had forecast. The test and measurement division of Danaher was the real laggard, as sales fell 2% year over year in that area. The life-sciences division, however, is doing quite well, and Danaher even announced the $480 million purchase of Siemens' clinical microbiology arm just yesterday. No word yet on whether Danaher has the resources and know-how to bring Barbie back from the dead in the event of her demise.